Retailer JD Sports has notched up record half-year results as profits jumped by nearly a fifth despite a tough retail market and difficult times during the heatwave.

The sportswear chain, which also owns Blacks and Go Outdoors, reported a 19% rise in pre-tax profits to £121.9 million for the six months to August 4.

It said like-for-like sales in its high street sports fashion stores were “marginally positive”, but lifted 4% including online trade.

The heatwave hit demand for outdoor goods at chains including Millets (PA)

Its outdoor brands – also including outlets such as Millets – endured a “difficult” first half after the prolonged summer heatwave dented demand.

Total like-for-like sales, including online, for its outdoor brands just scraped into positive territory, having initially risen by 7% in the first three months.

JD Sports said: “After a promising first quarter when our outdoor fascias benefited from the late winter, they have all had an extremely challenging second quarter with good growth in sales of lightweight shorts and T-shirts nowhere near able to compensate for a significant and understandable decline in jackets and other waterproof apparel.”

But JD said it believed the sales blow was a “one-off” and remains “more widely reassured for the longer term by further growth in sales of camping and other outdoor activities”.

Peter Cowgill, executive chairman of JD Sports, said: “Against a backdrop of widely reported retail challenges in the UK, it is extremely reassuring that the profitability in the UK and Ireland sports fascias has been further enhanced.

“This reflects the value of the investments that we have made over a number of years in developing a dynamic multi-channel proposition which marries the best of physical and digital retail.”

The firm said its global expansion continued apace in the past year, with 39 JD stores opened overseas, including 18 in Europe and 21 in the Asia Pacific region.

It has also recently secured its US market debut after taking over American sportswear company Finish Line in June for 558 million US dollars (£428 million) in what it has previously branded a “transformational” deal.

The group said it continues to see value in a high street store portfolio and does not expect to shed shops on a significant scale, although it is working with landlords to ensure “our portfolio of leases has the maximum flexibility and the lowest committed cost possible”.

On current trading, JD Sports said sales have continued at similar levels to those in the first half and the group remains on track for full-year forecasts.

It now has 390 sports fashion stores in the UK and Ireland, out of 2,184 globally, and 239 outdoor outlets.